US 3256647 A
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Description (OCR text may contain errors)
June 21, 1966 N. H. HUTTON 3,255,547
MEANS FOR CLEANING AND COOLING GRINDING APPARATUS Filed July 24, 1963 2 Sheets-Sheet 1 M FIG. Ia
NORMA/V H. HUTTO/V BY WZMQ M ATTORNEYS INVENTOR June 21, 1966 N. H. HUTTON 3,256,647
MEANS FOR CLEANING AND COOLING GRINDING APPARATUS Filed July 24, 1965 2 Sheets-Sheet 2 INVENTOR NORMA N H. HU T TON BY WWW ATTORNEYS United States Patent 3,256,647 MEANS FUR CLEANING AND COOLING GRINDENG APPARATUS Norman Horatio Hutton, Hove, England, assignor to Hydrol Chemical Company Limited, Brighton, England, a corporation of Great Britain Fiied July 24, 1963, Ser. No. 297,279 Claims priority, application Great Britain, Aug. 19, 1960, 28,800/ 6th 8 Claims. (Cl. 51-467) This is a continuation-in-part of now abandoned application Serial No. 131,759, filed August 16, 1961. p
This invention relates to the grinding of metals, ceramics and other materials which have to be subjected to abradin-g in the course of manufacture and has for its object to provide an improved construction or arrang ment designed to ensure the removal of accumulated debris including swarf, gritty material and other waste substances removed from a work-piece by abrasion and which would tend in the course of time to impede the grinding operation or cause deterioration of the surface of a grinding element.
It is also an object of the invention to provide means for ensuring the removal of the waste substances under all conditions of wear on the grinding element.
To avoid the disadvantages and to achieve the objects referred to in the preceding paragraphs the present invention provides a grinding arrangement having a jet or jets for the introduction of grinding fluid additional to the normal supply of fluid to a work-piece and so arranged that the fluid impinging on the surface of a rotary grinding element will loosen any solid deposits and thereby maintain the surface of the grinding element clean and facilitate the ultimate removal of waste material 'from the grinding apparatus.
Reference will now be made to the accompanying drawings which illustrate diagrammatically and by way of example, arrangements according-to the invention and in which:
FIGURE 1 illustrates in elevation one construction according to the invention and FIGURE 1a is a fragmentary elevation of a modified construction;
FIGURE 2 is an elevation illustrating a further modification; and
FIGURE 3 illustrates a modification of the adjust-able deflector plate shown in FIGURE 2.
Referring first to FIG. 1, a rotary grinding wheel a is disposed within a hood b shaped to enable a workpiece cI to be brought into contact with the grinding wheel at c in the usual manner. Hood b essentially is of conventional construction having a semi-circular, uniformly diametered plate portion b1 and depending flat sided parallel skirt portions b2 and b3. Portion bit is radially spaced from the periphery of wheel a and portions b2 extend over opposite sides of the grinding wheel as shown. The space between hood port-ion b1 and the periphery of wheel a is made relatively narrow for a purpose to be presently explained in detail.
A suitable nozzle 02 disposed externally of hood b conventionally is adapted to supply coolant liquid to the region where workpiece c1 engages the periphery of grinding wheel a. In such an arrangement as normally employed centrifugal force set up by the rotation of the grinding wheel tendsto dislodge residues from the grinding wheel but also to cause such residues to accumulate against the interior surfaces of the hood b. If these residues become detached from the interior surfaces of the hood and fall upon the grinding wheel they will detract from the efficient cutting action of the abrasive surfaces of the wheel. To avoid this happening, the present ice invention provides additional means other than at the point c where the workpiece is actually abraded to detach the debris from the grinding face of the wheel a and prevent the accumulation of grinding residues within the hood b.
The means employed for removing debris as shown in FIGURE 1 comprises a liquid coolant supply system having a discharge conduit (or a number of discharge conduits) a disposed in the upper part of the hood I) and to which the coolant fluid is supplied by the action of a pump 2 which withdraws the fluid from a storage tank f and passes it through a pipe g to the conduit d which is provided with a control valve h. As shown, conduit d comprises a straight tube d1 extending radially into hood portion b1 and terminating in a nozzle or jet i within the confined space between hood portion b1 and the periphery of wheel a. Preferably, nozzle i is located at a point in the hood portion 121 remote from the work piece and opens to direct the liquid coolant jet radially inwardly. The fluid is pumped through the nozzle 1 at such temperature and pressure as to eject coolant liquid in the form of a jet whose impact on the surface of the grinding wheel causes the debris to be dislodged from the grinding surface whilst atomization of the grinding fluid induced by the rotation of the abrasive wheel will counteract any tendency of the debris to accumulate and become attached either to the wheel or to the interior of the hood. By thus maintaining the debris in a finely divided and mobile condition, its removal with the grinding fluid as it leaves the apparatus is ensured. The control valve 11 enables the volume of grinding fluid-to be adjusted to suit the character of the material of the work-piece under treatment.
Where a grinding wheel of substantial width is employed, the jet and nozzle may be disposed at one side of the hood so as to project the liquid transversely across the surface of the wheel. Alternatively, as shown in FIG- URE 1a additional coolant nozzles may be employed as indicated at k.
When dealing with metals such as cast iron or alloys thereof which produce a large quantity of waste residue during grinding, it may be desirable to employ an additional pump in the tank 1 to boost the pressure at the nozzle or nozzles.
The arrangement above described in addition to ensuring removal of waste residues possesses the further advantage that the wetting by the grinding fluid of the wheel surface and subsequent absorption of the fluid into the matrix and interstices of the wheel produces conditions whereby the temperature in the cutting area at c is red-uced by the previously absorbed grinding fluid travelling out-wards by centrifugal force between the wheel and the work-piece. The reduction of temperature in the cutting area in conjunction with the re-absorption of coolant deflected by hood [2 onto the periphery of the grinding wheel tends to avoid distortion of the work-piece or metallurgical change and in addition promotes detachment of debris by contraction while residual coolant will be cushioned between the wheel and the Work-piece to lower the cutting temperature. 1
The explanation of the results above described is that coolant liquid directed on to the surface of a grinding (ii) The coolant liquid must be able to penetrate sufliciently into the surface of the grinding wheel to prevent it from becoming overheated and eventually distorted.
In obtaining the foregoing results, coolant liquid is introduced through the additional nozzle i within hood a as previously described. Owing to the narrow space between the peripheral surface of the grinding wheel and the inner surface of hood position b1, the liquid introduced through the nozzle i is not immediately lost but due to its velocity and the speed of rotation of the wheel the liquid rebounds or ricochets between the two opposed surfaces as indicated at d2 and is thus brought into repeated and intimate contact with the surface of the wheel, thereby cooling that surface sufliciently to loosen the accumulated debris which is eventually washed away as the liquid finally flows out of the space between the hood and the wheel. This operation overcomes a longstanding disadvantage as, due to the heating of the wheel under normal operation conditions, the particles of debris become tightly lodged in the small interstices in the rough surface of the wheel. The additional degree of cooling imparted by the arrangement according to the present invention causes a sufficient degree of contraction to occur in the wheel surface for the jet of coolant to dislodge the particles leaving the surface of the wheel cooled and in good grinding condition.
The grinding arrangements above described also possess the advantage of reducing the need for dressing the abrading surface resulting in more continuous production, higher output and better surface finishes than have been possible with arrangements hitherto employed.
In the modified construction shown in FIG. 2, a rotary grinding element a is disposed within a housing or hood [2' with means external thereto for bringing a workpiece c1 into contact with the grinding surface as described with reference to FIG. 1. Coolant liquid is directed by a nozzle c2 onto the area of contact between the workpiece c1 and the grinding element a in the normal manner and in addition a discharge conduit d for coolant liquid is also arranged within the hood b for directing such liquid either radially or tangentially onto the surface of the grinding element over an area remote from the position of the workpiece Hood b and conduit d are respectively of the same construction as hood b and conduit d with like reference characters identifying like elements. It has been found in practice that as the diameter of the grinding element a becomes reduced by wear, the operation of the additional jet of liquid from conduit d becomes progressively less effective in producing the conditions within the hood which are necessary for adequate removal of debris and penetration of the grinding surface by the coolant liquid. To deal with this difficulty the present invention provides a deflector l conveniently in the form of a plate of curvature concentric with that of the grinding element and hood within which the deflector plate is adjustably mounted so that it can be moved at intervals to maintain a position in predetermined concentric relationship with the grinding element a as the diameter thereof gradually decreases during use.
A convenient mode of mounting the deflector plate is to form at its centre a sleeve m which passes adjustably over tube d of conduit d which extends to the exterior of the hood b and through a guide or bracket 12 mounted on the hood and carrying a set-screw 0 or equivalent devise arranged to bear upon the exterior of the sleeve in and retain it in any desired position of adjustment. Thus, in the initial stage of operations, the deflector plate I can occupy a position in contact wtih the inner surface of the hood and thereafter by slackening the set screw 0 the deflector plate I and conduit d can be moved inwards at intervals to maintain them in approximately constant spacing from the grinding wheel surface, their position being maintained by tightening the set-screw 0 after each each adjustment.
As the diameter of the grinding wheel is decreased by wear its periphery ceases to be concentric with the deflector plate and in addition to the adjustment already described it is preferable to employ the push rods 1) and p shown in FIG. 2. These push rods are mounted in sleeves q and q carried by the hood b through which they project so that as the deflector plate is moved inwards pressure can also be applied to the push rods to bend the ends of the deflector plate to increase its curvature and maintain it in substantially concentric relationship with the grinding whel. The push rods can be secured in their adjusted position by clamping screws 1' and r' passing through the sleeves q and q and carrying wing rods s and s for manual operation.
The deflector plate I must be so arranged as to ensure ricochet of the jet stream and diffusion on to the peripheral area. This can be contrived in two ways:
(a) An increase in velocity of the jet stream by additional pressure.
(b) Moving the jet, with or without the deflector, sufficiently near to the periphery to ensure impingement and rebound.
Further the deflector plate I can be interchangeable so as to approximate the radius of the grinding element as it wears away by the process of abrasion. Alternatively, a compromise solution by using a single deflector plate could be used, the radius of which would be based on the estimated diameter of the grinding wheel at the termination of its useful life. For instance with a 24" diameter wheel, the radial distance to the periphery of the wheel would be 12". The radius of the deflector would be made to conform to the estimated diameter of its useful life, which would be estimated to be 18" in diameter. The radius of the deflector would thus be made to conform to a wheel size of approximately 18". This would be adjusted to suit a new wheel so as to a ensure the extreme ends of the deflector to maintain a small working clearance of approximately a sixteenth of an inch.
The arrangement shown in FIG. 2 ensures that the jet stream is always directed where it will penetrate the air flow generated by the high speed of the grinding wheel and thereby make contact with the wheel periphery with sufficient force to enter the surface pores of the wheel. Owing to the narrow space which is maintained between the surface of the grinding wheel and the inner surface of the deflector, the coolant liquid introduced through the jet in the plate is not immediately lost, but due to its velocity and the speed of rotation of the wheel, the liquid rebounds or ricochets between the surfaces of the wheel and the plate and is thus brought into repeated and intimate contact with the surface of the wheel, thereby cooling that surface sufliciently to loosen the accumulated debris which is eventually washed away as the liquid flows out of the space between the deflector plate and the wheel. This operation overcomes the disadvantage hitherto experienced that due to the heating of the grinding wheel under normal operating conditions, particles of debris become tightly lodged in the interstices in the rough surface of the wheel. The additional cooling imparted by the arrangement according to the invention causes a suflicient degree of contraction to occur within the grinding wheel surface for the jet of coolant to dislodge the particles embedded and leave the surface of the wheel cooled and in good grinding condition.
The invention possesses the further advantage that the cooling of the grinding wheel surface and its preservation in a good grinding condition maintains efficient operation and prevents overheating, distortion or deterioration of the workpiece.
The hood above described may embody two stationary baffles arranged to deflect surplus liquid which is caused to fall through the base of the hood thereby protecting the operator from such liquids being thrown outwards by rotation of the wheel in the region of the workpiece.
Referring now to FIGURE 3, a further modification resides in the provision of a slot f in the deflector plate to allow coolant to pass into the space external to the deflector plate and operate to remove any debris which may tend to accumulate on the inner surface of the hood.
What is claimed is:
1. In grinding apparatus, a rotatably mounted grinding element, means for supplying coolant liquid to the grinding area where a workpiece is brought into contact with said element, a hood partially enclosing said grinding element, a nozzle mounted in the hood for directing a jet of coolant liquid against the periphery of said grinding element within said hood, a curved deflector plate mounted within the hood concentrically with the grinding element, means for adjusting the positions of said nozzle and deflector plate, said means for adjusting the position of said deflector plate being effective to enable the radial distance of the space between said deflector plate and the periphery of the grinding element to be varied as the diameter of said grinding element becomes reduced by wear and means for securing the said nozzle and deflector plate in their adjusted positions.
2. In grinding apparatus as defined in claim 1, the provision of a sleeve formed on the deflector plate and engaging over said nozzle which projects through to the interior of the deflector plate, a bracket on the exterior of the hood through which said sleeve and nozzle pass and means carried by said bracket for engaging and locking the sleeve and nozzle in adjusted positions.
3. In a grinding apparatus having a rotatably mounted grinding wheel, hood means partially receiving said grinding wheel and having a deflector surface facing and spaced from the periphery of said wheel to define a narrow space therewith, means providing a supply of liquid coolant, a nozzle connected to said supply and disposed in said space to direct a jet of coolant liquid of predetermined velocity against the periphery of said grinding wheel covered by said hood means to penetrate into the periphery of said grinding wheel, said nozzle and deflector surface being so arranged that said jet repeatedly rebounds back and forth between said deflector surface and said wheel over a predetermined peripheral segment of said wheel in said space.
4. The grinding apparatus defined in claim 3 wherein said nozzle extends through said hood ,means and is so positioned as to direct said jet radially inwardly.
5. The grinding apparatus defined in claim 4 wherein said hood means comprises a hood and curved plate flector surface for radial displacement independently of each other to compensate for wear of said wheel.
8. In a grinding apparatus having a rotatably mounted grinding wheel, a hood partially receiving said grinding wheel and being spaced from the periphery thereof, plate means disposed radially between said hood and the periphery of said grinding wheel and having a curved deflector surface facing and concentrically spaced radially from the periphery of said grinding wheel to delimit a narrow space therewith, means providing a supply of liquid coolant, a nozzle connected to said supply of liquid coolant and disposed in said narrow space to direct a jet of coolant liquid of predetermined velocity against the periphery of said grinding wheel covered by said hood, said nozzle and said deflecting surface being so arranged that said jet repeatedly rebounds back and forth between said deflector surface and the periphery of said grinding wheel over a predetermined peripheral segment of said grinding wheel in said narrow space, and means adjustably mounting said plate means for radial displacement relative to said grinding wheel to enable the radial distance of said narrow space to be varied to compensate for wear of said wheel.
References Cited by the Examiner UNITED STATES PATENTS 385,666 7/1888 Hadley 51-267 2,307,019 1/1943 Cebik 51-267 2,361,550 2/1944 Krueger 5l-'272 3,123,950 3/1964 Kuris et al. 51-267 X FOREIGN PATENTS 701,220 1/ 1941 Germany.
ROBERT C. RIORDON, Primary Examiner.
LESTER M. SWINGLE, Examiner.
I. A. MATHEWS, Assistant Examiner.